I used to work at a search engine company, so I know this is a very difficult problem, and I honestly do believe Google is trying their hardest, but clearly not enough, and you have to wonder if it's partly because they are making money in many cases from those scraper sites (IE they have Google ads).
My site - http://www.ausedcar.com used to be in the top 10 on Google for the very popular keywords "used cars" but I've been knocked back to around #45 over the years simply because everyone in front of me uses black hat SEO. Including major million dollar companies! The only difference is that Google is not going to blacklist a major company, while they probably would blacklist me, so there is essentially no way for the little guy to do anymore then hope Google will give some scraps off the table.
The fact that you simply can't do a product review search on Google anymore without getting spam is serious trouble for Google. Unfortunately Bing seems to copy the same algorithm, if they were the "Anti-spam" engine, they could gain real ground.

Let's look at where stackoverflow.com traffic came from for the year of 2010. When 88.2% of all traffic for your website comes from a single source, criticizing that single source feels … risky. And perhaps a bit churlish, like looking a gift horse in the mouth, or saying something derogato...